Abstract
Gas turbines in IGCC plants burn syngas that is composed of hydrocarbons, mixtures of H2 and CO, and also handle diluent gases such as N2, CO2, and steam, which may be injected into the combustor in order to increase the turbine mass flow and reduce NOx emissions. Future developments envision the use of syngas and hydrogen in various proportions as an approach to minimizing carbon emissions. In all such fuel scenarios, it is desirable to use the highest possible turbine rotor inlet temperature (RIT) in order to maximize overall efficiency. However, because of the inherently detrimental effects of maximized RIT on the lifetime/reliability of the turbine hot gas path components, as well as the associated complications in combustor design for optimum use of such different fuels, it is desirable to know the effects of fuel composition and combustion conditions on the temperatures experienced by the critical components. This study deals with the accurate prediction of hot gas path component surface and interface temperatures as a function of fuel composition and combustion conditions, which have direct implications for component cooling, the rate of strength degradation of structural components and interaction of coatings with those components, hence the service lifetime of protective coatings. The approach involves integration of thermodynamic models of turbine performance (compressor, combustor) with blade cooling models (with and without thermal barrier coatings). The modular structure of a gas turbine allows straightforward implementation of models for various fuel/combustion scenarios, and for the components of interest. Complications include the requirement for detailed analysis that considers the actual geometrical configurations of some components, in order to increase the accuracy of numerical simulations. Several implementation possibilities are discussed, as well as the current status of the computer program development, which is illustrated by some preliminary results.
